package solution.Title_1_10;

import pojo.ListNode;

/**
 * @author FreyaZ
 * @version 2018-01-01

    2.
    You are given two non-empty linked lists representing two non-negative integers.
    The digits are stored in reverse order and each of their nodes contain a single digit.
    Add the two numbers and return it as a linked list.
    You may assume the two numbers do not contain any leading zero, except the number 0 itself.

    Example

    Input: (2 -> 4 -> 3) + (5 -> 6 -> 4)
    Output: 7 -> 0 -> 8
    Explanation: 342 + 465 = 807.

 */
public class AddTwoNumbers {
    public static ListNode addTwoNumbers(ListNode l1, ListNode l2) {
        ListNode result = null;
        ListNode head = null;
        int carryBit = 0;

        while (l1 != null || l2 != null) {
            int sum = (l1 == null ? 0 : l1.val) + (l2 == null ? 0 : l2.val);
            int currentVal = (sum + carryBit) % 10;
            carryBit = (sum + carryBit) / 10;

            l1 = l1 == null ? null : l1.next;
            l2 = l2 == null ? null : l2.next;

            if (result == null) {
                result = new ListNode(currentVal);
                head = result;
            } else {
                head.next = new ListNode(currentVal);
                head = head.next;
            }
        }

        if (carryBit != 0) {
            head.next = new ListNode(carryBit);
        }

        return result;
    }
}
